Mineral Tenacity and Fracture

Fracture

Fracture Description

Brittle - Conchoidal

Very brittle fracture producing small, conchoidal fragments.

Brittle - Irregular

Very brittle fracture producing irregular fragments

Brittle - Subconchoidal

Brittle fracture with subconchoidal fragments

Brittle - Splintery

Brittle fracture leaving splintery fragments.

Brittle - Sectile

Brittle fracture with slightly sectile shavings possible.

Brittle

Generally displayed by glasses and most non-metallic minerals.

Brittle - Uneven

Very brittle fracture producing uneven fragments.

Conchoidal

Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Conchoidal - Irregular

Irregular fracture producing small, conchoidal fragments.

Conchoidal - Uneven

Uneven fracture producing small, conchoidal fragments.

Elastic

Fragments which spring back after bending.

Earthy

Dull, clay-like fractures with no visible crystalline affinities, (e.g. howlite).

Even

Flat surfaces (not cleavage) fractured in an even pattern.

Fibrous

Thin, elongated fractures produced by crystal forms or intersecting cleavages (e.g. asbestos).

Fragile

Crystals with a delicate and easily injured structure.

Flexible

Flexible fragments.

Friable

The crumbly disintegration of earthy materials or highly fractured minerals.

Granular

Fracture surfaces produced by aggregated minerals, (e.g. granite).

Hackly

Jagged, torn surfaces, (e.g. fractured metals).

Irregular

Flat surfaces (not cleavage) fractured in an irregular pattern.

Micaceous

Fracture of flexable micaceous cleavage fragments.

Malleable

Deforms rather than breaking apart with a hammer.

None

No fractures

Plastic

Deforms like soft, plastic materials.

Plastic - Splintery

Thin, soft flexable, elongated fractures produced by intersecting good cleavages or partings (e.g. hornblende).

Regular

Flat surfaces (not cleavage) fractured in a regular pattern.

Sub Conchoidal

Fractures developed in brittle materials characterized by semi-curving surfaces.

Sectile

Curved shavings or scrapings produced by a knife blade, (e.g. graphite).

Splintery

Thin, elongated fractures produced by intersecting good cleavages or partings (e.g. hornblende).

Sugary

Fracture surfaces produced by finely aggregated minerals, (e.g. massive anhydrite).

Tough

Difficult to break apart as shown by fibrous minerals and most metals.

Unknown

Minerals too small to observe fractures.

Uneven

Flat surfaces (not cleavage) fractured in an uneven pattern.

Weak

Hard to handle without causing serious harm or damage.